Current back-up or reverse systems in automobiles include sensors that alert the driver of objects that are in the vehicle's backing path (e.g., a person, another vehicle, a shopping cart, etc.). The technologies most often used today consist of either image sensors (e.g., CCD or CMOS-based cameras) or distance sensors (ultrasonic, radar, active IR, passive IR) that calculate the distance from the rear of the vehicle to the object of interest.
Distance-sensing technologies typically indicate distance using audible cues, visual displays, or both. The audible cue is usually a beeping tone that increases in rate as the vehicle (in particular, the vehicle's bumper) gets closer to the object of interest. The beep becomes a solid tone when the object is very close to the vehicle (e.g., less than twelve inches). Visual displays typically include a varying numbers of LED's. As the object gets closer to the bumper, more LED's are illuminated. When the object is very close to the bumper, all of the LED's are illuminated and often will flash on/off.
Image sensing technologies utilize images captured by a camera (or similar device). The images are displayed on a liquid crystal display (“LCD”) or similar display either in the center stack of the instrument panel, in the instrument cluster, or in the rear-view mirror. Additional information can be added to the displayed image (or specifically, lines that represent a track (or path) that the vehicle is traveling, while in reverse, are added to the viewable output. In addition to the vehicle track, some displays also show a center line between the vehicle track lines to aid a driver trying to hitch a trailer to a host vehicle. A more recent update to the vehicle track overlay is to show the track the vehicle will take, based on a position of the steering wheel, assuming the steering wheel remains in its current position).